more than likely it's an exhaust manifold gasket, the reason it gets quieter when warm is because heat expands the metal and closes the gap. Normaly they sound like a ticking. The exhaust manifold can be cracked also, or the bolts loose. good luck

Thank you for your help. It sounds like the problem except I don't hear the ticking. It is just really, really loud! I have put it off for a long time, but it is so loud I will have to take to have repaired. Just hope it's not too expensive. Have a great day, and I appreciate your time. Sincerely, Christine